This application relates to functionally graded cemented tungsten carbide materials that contain a metal binder gradient. The metal binder can be cobalt, nickel, iron or alloy thereof. Such materials may be used for metal cutting tools, rock drilling tools for oil exploration, mining, construction and road working tools and many other metal-working tools, metal-forming tools, metal-shaping tools, and other applications. For background information, the reader should consult U.S. Patent Application Publication No. 2005/0276717, which patent application is expressly incorporated herein by reference.
As explained in the prior patent publication noted above, it is desirable to construct a cemented tungsten carbide material (“WC” material) that includes an amount of metal binder. It is desirable to construct a cemented tungsten carbide material that has a combination of toughness and wear-resistance.
Cemented tungsten carbide, consisting of large volume fractions of WC particles in a metal binder matrix, is one of the most widely used industrial tool materials for metal machining, metal forming, mining, oil and gas drilling and all other applications. Compared with conventional cemented tungsten carbide, functionally graded cemented tungsten carbide (FGM cemented tungsten carbide) with a metal binder gradient spreading from the surface to the interior of a sintered piece offers a superior combination of mechanical properties. For example, FGM cemented tungsten carbide with a lower metal binder content in the surface region demonstrates better wear-resistance performance, resulting from the combination of a harder surface and a tougher core. Though the potential advantages of FGM cemented tungsten carbide are easily understood, manufacturing of FGM cemented tungsten carbide is however a difficult challenge. Cemented tungsten carbide is typically sintered via liquid phase sintering (LPS) process in vacuum. Unfortunately, when cemented tungsten carbide with an initial metal binder gradient is subjected to liquid phase sintering, migration of the liquid metal binder phase occurs and the gradient of metal binder is easily eliminated.